1. Field of the Invention
The present invention concerns a procedure for processing biological products in order to modify their biological, mechanical and textural properties in order, in particular, to prepare souffle-type food products and dehydrated food products or in order to use or improve the processes for the extraction of essences or essential oils or, in addition, for carrying out bactericidal treatments.
2. Description of the Related Art
Procedures are known in the prior art for processing biological products in order to modify their texture, particularly dehydration procedures, that comprise:
a step involving the introduction of the biological products into a hermetic enclosure; PA1 a step involving the heating of the products that have been deposited in the enclosure, whereby the aforementioned products are subjected to a pressure that is greater than the pressure of the atmosphere; PA1 a subsequent step of relieving the excess pressure. PA1 evacuating the enclosure in which one deposits the products, that are to be dehydrated, together with an adsorption device until a partial pressure of the air is obtained in the aforementioned enclosure that is between 1 and 2 mbars; PA1 increasing the total pressure in the enclosure to between 7 and 200 mbars via the introduction of a coolant gas; PA1 maintaining the desired pressure; PA1 stopping the operation; PA1 pressurizing the enclosure and the adsorption device to the pressure of the atmosphere. PA1 evacuating the enclosure in which the dressed products are deposited on plates; PA1 heating the wall of the enclosure; PA1 introducing water vapor into the enclosure; PA1 re-evacuating the enclosure; PA1 heating the plates; PA1 re-pressurizing the enclosure to the pressure of the atmosphere. PA1 introducing the pieces, that are to be dried, into the enclosure that is then sealed hermetically; PA1 increasing the internal temperature of the enclosure to a value between 50.degree. and 90.degree. C.; PA1 stabilizing or equilibrating the internal temperature of the enclosure with that of the pieces by carrying out a step in which time is allowed to pass by with a duration of at least one minute; PA1 then subjecting the interior of the hermetic enclosure to a partial vacuum of between 0.5 and 0 bar over a time period of between 30 seconds and 3 minutes while ensuring a forced circulation of air in the interior of the enclosure and over the pieces that are to be dried; PA1 re-subjecting the interior of the enclosure to the ambient pressure of the atmosphere.
European patent EP525213 describes such a process for the dehydration of pieces of vegetables, fruits or cereal grains that comprises several steps as follows:
Another patent of the prior art, European patent EP435302, describes a procedure for the total or partial dehydration of pieces of entire biological products of the vegetable, fruit or flower type, a dehydration device and the corresponding products, whereby the procedure comprises a succession of steps:
European patent EP0421902 divulges a process for drying pieces of wood, whereby the process comprises:
Another document of the prior art, French patent FR2618981, describes a procedure for processing fresh vegetables. According to this document, one processes the vegetables with steam in an air-tight enclosure and the enclosure is evacuated after processing.
This document states that communication between the source of the vacuum and the enclosure slowly reduces the pressure in the enclosure, whereby the pressure-reduction phase lasts approximately two minutes and forty five seconds or even nine minutes in another experiment that is mentioned in this prior art document.
In a general manner, the pressure-reduction phase that is provided in the prior art documents is intended only to produce a thermodynamic evaporation effect under vacuum.
Another document of the prior art, European patent EP0455976, divulges a process for drying, whereby drying is accompanied by a pressure-reduction phase over a period of less than 30 seconds.
This document does not concern a process that is designed to modify the texture of the plant-based product but a process for drying products.
The first sentence of the patent EP0455976 and the preamble of the main claim states, without ambiguity, that the subject of the invention is the drying of biological products.
The teaching of this prior art document corresponds to a drying process that is accompanied (and not therefore followed) by a pressure-reduction phase extending over a period of less than 30 seconds. This period of time constitutes an order of magnitude that is significantly different from the duration of the sharp pressure-reduction that is of the order of one second.
The technical effect of the slow reduction in pressure according to EP455976 is also mentioned in this document: it has the objective of bringing about the "opening" of the cells in such a way as to permit equilibration of pressures with a view to better diffusion of water vapor (see page 3, lines 1-5 of patent application EP455976). It appears by means of experimentation that reductions in pressure that are effected over times of the order of 30 seconds are translated into a simple improvement of the diffusion of water vapor that assists the drying phase but does not modify the microstructure of the material in any way.